| 摘要 |
PROBLEM TO BE SOLVED: To provide a BBW type brake system having two hydraulic pressure systems, which can secure the function of one hydraulic pressure system when the other hydraulic pressure system fails. SOLUTION: Braking is carried out by the brake hydraulic pressure of a second hydraulic pressure system transmitted to a wheel cylinder from a master cylinder through the front liquid chamber 39B of a motor cylinder 23 when a first hydraulic system continuous with the rear liquid chamber 39A of the motor cylinder 23 fails and opens to atmosphere when braking by the brake hydraulic pressure generated by the master cylinder at the time of failure of the motor cylinder 23. At that time, a front supply port 49A communicating with the rear liquid chamber 39A which is made open to atmosphere by failure through a rearward front second cup seal C4 communicates with a reservoir without communicating with the master cylinder, so that the brake hydraulic pressure generated by the master cylinder is prevented from leaking through a front supply port 49B, the front second cup seal C4, and the rear liquid chamber 39A, and braking by the second hydraulic pressure system continuous with the front liquid chamber 39B of the motor cylinder 23 is secured. COPYRIGHT: (C)2008,JPO&INPIT
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